A security seal is a single-use closure device that guarantees the tamper-proofing of a container: a parcel, container, lorry, crate, or bag. Once fitted, it cannot be removed without being destroyed. Any opening leaves a visible sign of tampering. It therefore performs two complementary functions: physically securing access and tracing that container through a unique number.
The principle relies on a one-way locking mechanism: you tighten; you never loosen. To reopen, you have to cut the seal, which makes any breach immediately detectable. It is this logic of proof that distinguishes a true seal from a simple closure.
Seals are classified according to their resistance capacity. Indicative seals signal an opening but break by hand. Barrier seals offer real mechanical resistance and require a cutting tool. Sequential numbering, barcodes, or QR codes then make it possible to link each seal to a container and to a transport document.
Note: Before comparing models, first identify your real need. The useful benchmark remains "Which security seal for which use", because an e-commerce parcel and a maritime container do not require the same level of protection.